A developing device includes a developer tank and a developing roller. An internal space of the developer tank is divided into a first conveying path, a second conveying path, a first communication path, and a second communication path by a partition wall. In the first conveying path, there is disposed a first developer conveying section that conveys the developer within the developer tank in a conveying direction X. In the second conveying path, there is disposed a second developer conveying section that conveys the developer within the developer tank in a conveying direction Y. The first developer conveying section includes an inner spiral blade, an outer spiral blade, an upstream spiral blade, a rotation tube, a delivery portion, support members, and a first gear. The rotation tube has an admission port portion and a discharge port portion.